Boise State running back Jay Ajayi (27) celebrates after his touchdown during the first half of the Mountain West Conference championship NCAA college football game against Fresno State in Boise, Idaho, on Dec. 6, 2014.
Otto Kitsinger
AP

Boise State running back Jay Ajayi (27) celebrates after his touchdown during the first half of the Mountain West Conference championship NCAA college football game against Fresno State in Boise, Idaho, on Dec. 6, 2014.
Otto Kitsinger
AP

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Ajayi, a dual-threat back who rushed for more than 1,800 yards as a senior, has a knee issue. And depending on whom you believe, it might be a big one.

He tore his ACL in 2011, and the knee reportedly sustained cartilage damage that can never be fixed.

But for the Dolphins, who made five selections Saturday — including four in the fifth round — Ajayi’s scary medical history “was not an issue,” assistant general manager Eric Stokes said.

Said Ajayi: “I know that with my knee and with the way I make sure that I handle it, I will play for a long time, and I’m excited to see how my future unfolds.”

Still, it was telling that the Dolphins waited until Round 5 to take him on a day largely dedicated to filling holes.

They selected Arizona State guard Jamil Douglas in the fourth round, before taking two corners (Memphis’ Bobby McCain and Michigan State’s Tony Lippett) and Minnesota safety Cedric Thompson in the fifth. The Dolphins did not own a sixth- or seventh-round pick, and were done with the draft around 3 p.m. Saturday.

▪ Douglas (pick No. 114) has the best chance of any third-day pick to win a starting job as a rookie.

Douglas, who played both guard and tackle for the Sun Devils, will line up at left guard when rookie minicamp begins in the coming days. Left guard also happens to be the most tenuous position on the team, as Dallas Thomas is ripe to be supplanted after a brutal 2014 season.

“We like where we are there,” Dolphins general manager Dennis Hickey said. “It’s great to add Jamil Douglas. We firmly believe in our philosophy about having competitive environments, and guys that we have here are going to compete, guys that we bring in are going to compete, and that’s the beauty of the NFL.”

And he has a knack for making plays. McCain returned four interceptions for touchdowns in his career at Memphis, and had 11 picks in the past two seasons. He could eventually replace Brent Grimes, who turns 32 this summer.

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“I’m really smart,” McCain said. “I’m not the tallest guy, I’m not the fastest guy, but I’m probably the most competitive guy. I’m not going to back down on anyone; I’m a player with a good head on my shoulders who is going to play with a chip on my shoulders as well.”

▪ The Dolphins have had success with fifth-round safeties. Reshad Jones was taken in that round five years ago.

The team hopes it has unearthed another gem in Thompson (pick No. 150), a free safety from Minnesota who didn’t receive an invitation to the Combine. But at the Gophers’ Pro Day, he ran in the 4.4s (seconds) in the 40-yard dash and jumped 40 inches.

▪ Lippett (pick No. 156) was a two-way player for Michigan State, but the Dolphins have one role in mind: cornerback.

His measurables (6-2, 192 pounds, 4.61 seconds) are in the same ballpark of another tall corner once selected in the fifth round: Seahawks star Richard Sherman.

Still, no pick generated more buzz than Ajayi, who buoyed the Dolphins after missing out on Georgia standout Todd Gurley in the first round.

“Watching the draft, I did think I was going to go earlier, so I definitely was disappointed,” Ajayi said. “But at the same time, I can only control what I can control. I know right now, at this day, I am extremely healthy and I’m ready to go into camp and contribute right away. I’m excited that the Dolphins took a chance on me. I’m excited to prove a lot of people wrong and prove the Dolphins right.”

Dolphins picked Saturday

NAME

COLLEGE

POS.

RD/PICK

Jamil Douglas

Arizona St.

OG

4/114

Bobby McCain

Memphis

CB

5/145

Jay Ajayi

Boise St.

RB

5/149

Cedric Thompson

Minnesota

FS

5/150

Tony Lippett

Michigan St.

WR

5/156

Dolphins’ Saturday selections

Round 4, Pick 114

Jamil Douglas, Guard

College: Arizona State.

Ht/Wt: 6-4, 304.

Comment: Douglas played left tackle last year, but will compete with Dallas Thomas, Jeff Linkenbach and others for starting left guard job.

Round 5, Pick 145

Bobby McCain, Cornerback

College: Memphis.

Ht/Wt: 5-9, 195.

Comment: Models his game after another diminutive cornerback — the Dolphins’ Brent Grimes. Now they’re teammates.

Round 5, Pick 149

Jay Ajayi, Running Back

College: Boise State.

Ht/Wt: 6-0, 221.

Comment: On talent alone, should have been a second-day pick. But fell to the fifth round because of concerns over a knee injury.

Round 5, Pick 150

Cedric Thompson, Safety

College: Minnesota.

Ht/Wt: 6-0, 208.

Comment: Started all 13 games as a senior (83 tackles). Could see playing time from scrimmage if Louis Delmas (knee) has a setback.

Round 5, Pick 156

Tony Lippett, Cornerback

College: Michigan State.

Ht/Wt: 6-2, 192.

Comment: Was the Spartans’ MVP after catching 11 touchdown passes as a receiver. With the Dolphins, he will be asked to knock those passes down.